FIG. 1 shows features of a conventional cable distribution system 100. The system 100 includes a head-end center 102 that receives media content from one or more information sources 104. The head-end center 102 forwards the media content to a plurality of clients (such as exemplary client 106) via a cable distribution infrastructure 108. The cable distribution infrastructure 108 may deliver the media content through a coaxial cable infrastructure. Alternatively, in a hybrid case, the cable distribution infrastructure 108 may deliver the media content through a combination of fiber-optic infrastructure and coaxial cable infrastructure. This hybrid solution is referred to as a Hybrid Fiber Coax (HFC) system. Although not shown, the cable distribution infrastructure 108 may also conventionally adopt a distributed architecture by including a plurality of distribution nodes. As to the client-side part of the system 100, the client 106 may include a set-top box 110 for receiving and processing the media content. The set-top box 110 supplies processed media content to a presentation unit 112 (such as a television set) for output to a user.
In one well known approach, the system 100 delivers media content (such as television programs) over a plurality of channels. For example, the system 100 may conventionally partition an assigned range of frequencies into a plurality of channels. In the U.S., 6 MHz-wide frequency segments may be used, with each segment being separated from its neighboring segments by 6 MHz. The system 100 can then transmit different media content over these respective 6 MHz segments.
More specifically, bandwidth excerpt 114 shows a known manner in which the system 100 may allocate channels within an available range of frequencies. As shown, the system 100 may allocate a lower-frequency portion of the available bandwidth to transmitting a series of analog channels. The system may allocate a higher-frequency portion of the bandwidth for transmitting a series of digital channels. In the analog portion of the spectrum, each 6 MHz segment of bandwidth corresponds to a single channel. In the digital portion of the spectrum, each 6 MHz segment of bandwidth can carry plural channels. The head-end center 102 can multiplex together digital channels into a single transport stream. In the case of the digital channels, the head-end center 102 commonly uses quadrature amplitude modulation (QAM) to modulate media content for transmission over the cable infrastructure 108. More specifically, the head-end center 102 can multiplex together a plurality of digital channels into a single transport stream and convey these channels over a QAM signal on a 6 MHz carrier.
In operation, a user generates a channel tune event in conventional fashion, e.g., by selecting a channel with a remote control device (not shown). In response, the set-top box 110 uses a tuner 116 to selectively extract desired media content from one of the channels. The tuner 116 performs this task by adjusting a band pass filter such that content delivered over an identified frequency is selectively extracted from a received broadcast signal. FIG. 1 represents this tuning behavior using a double-headed arrow 118, where the double-headed arrow 118 denotes that the tuner 116 effectively moves along the frequency spectrum to extract desired information from the received broadcast signal. In the case of digital channels, the set-top box 110 also employs a demultiplexer (not shown) to extract the desired channel from the multiplex of digital channels.
FIG. 2 shows the operation of the system 100 in a different manner. Namely, this figure shows that four streams of media content, i.e., A, B, C, and D, are assigned to four different channels, W, X, Y, and Z. The tuner 116 selects desired media content by moving its band pass filter to extract a desired segment of the frequency spectrum.
The above-described type of conventional system 100 has enjoyed substantial success over the years, as evidenced by a large population of users who currently subscribe to this kind of service. At the same time, the market has also seen the significant growth of computer-based systems for delivering content to users over packet-based networks. The Internet represents the most dramatic example of such technology. Computer-based systems offer the promise of providing services that surpass traditional cable systems in terms of versatility, complexity, user-interactivity, and so on.
Computer-based systems may use a different delivery paradigm than the communication model described above. Namely, a typical computer-based system may employ a unicast mode to deliver content. In this mode, an information source delivers a media content item to a particular user over a dedicated communication coupling. For example, consider the case of a user who relies on a dial-up or digital subscriber line (DSL) connection to receive media content from an Internet-accessible source. This user may connect to the source over a dedicated communication socket in conjunction with a dedicated telephone line into the user's home. In contrast, as described above, the system 100 performs client-side selection to extract a portion of a broadcast signal.
To avoid losing market share, the cable industry is actively looking for ways to address the growing popularity of computer-based media delivery systems. As appreciated by the present inventors, the cable industry has invested substantial amounts of financial and technical resources in cable infrastructures, making it difficult to simply abandon this technology in favor of Internet-based models.